Measurement method, measurement apparatus, exposure method, and exposure apparatus

ABSTRACT

To perform high-speed and highly accurate measurement by setting desired measuring conditions for each measuring object. In an alignment sensor of exposure apparatus, in the case of performing position measurement for a plurality of sample shots, measurement is performed by changing the measuring conditions, in response to a measuring axis direction, a mark or a layer whereupon a mark to be measured exists. At that time, for the measuring objects to be measured under the same measuring conditions, for example, a position in a Y axis direction and a position in an X axis direction, measurement is continuously performed. When the measuring condition is changed, a baseline value is remeasured. The changeable measuring conditions are wavelength of measuring light, use and selection of a retarder, NA and σ of an optical system, a light quantity of measuring light, illumination shape, signal processing algorithm, etc.

TECHNICAL FIELD

This invention relates to a measurement method and a measurementapparatus suitable for measurement of the positions of marks formed onmask or substrate in photolithography process when manufacturingsemiconductor devices and other electronic device, as well as to anexposure method and exposure apparatus used to measure the positions ofmarks formed on a mask or a substrate by this measurement method and toperform exposure.

BACKGROUND ART

In the manufacture of semiconductor devices, liquid crystal displaydevices, CCDs and other image-capture devices, plasma display devices,thin film magnetic heads, and other electronic devices (hereafterseverally called “electronic devices”), an exposure apparatus isemployed to project image of a fine pattern formed on a photomask or areticle (hereafter “reticle”) onto a semiconductor wafer, a glass plateor similar (hereafter “wafer”) onto which a photoresist or otherphotosensitive material has been applied, to perform exposure. At thistime, the reticle and wafer must be positioned (aligned) with highprecision, and the pattern of the reticle must be superposed onto thepattern of the wafer with high precision. In recent years, there hasbeen rapid progress toward finer pattern and higher integration density,and so ever-higher exposure precision has come to be demanded from suchexposure apparatus. For this reason, ever stricter demands have beenimposed on alignment precision as well, and higher alignment precisionis sought.

In the conventional art, wafer position measurement has been performedby measuring the position of a positioning mark (alignment mark) formedon the wafer. As the alignment system used to measure the position ofthese alignment mark, for example, an off-axis alignment sensor of a FIA(Field Image Alignment) system, which irradiates the mark using light ofbroad wavelength band using a halogen lamp or similar as a light source,capturing the reflected light with a CCD camera or similar, andperforming image processing of the image data of alignment mark thusobtained to measure mark position, are well known. By means of thealignment sensor of such the FIA system, thin film interference by theresist layer does not easily influence the result, and the position ofan aluminum mark, an asymmetrical mark and similar can also be detectedwith high precision. Methods have also been disclosed enabling imagecapture of mark with high contrast by selecting the wavelength of thedetection light (see for example Patent Reference 1) and for detectingwith high precision the position even of mark with small step heightusing the light reflected from the mark, by emphasizing change in thedetection light (see for example Patent Reference 2); and variousmethods have been proposed for performing alignment with higherprecision.

However, when for example positioning the wafer and shot areas, thepositions in the X-axis direction and Y-axis direction of each of aplurality of prescribed marks on the same wafer are measured, and basedon the results EGA computations are for example performed to finallyobtain the position information for control. That is, in a series ofalignment processing (mark measurement processing), it is often the casethat a plurality of position measurement processing operations(measurement processes for a plurality of marks) are normally performed.However, in alignment measurement methods of the conventional art,during a series of alignment measurement processing operations for thesame wafer, only a single set of measurement conditions, set in advance,is applied to a plurality of objects for measurement (marks) whenperforming measurement processing. That is, appropriate measurementconditions have not been set for each measurement object to performposition measurements or similar.

More specifically, when for example a plurality of marks are formed indifferent layers on a wafer, or when the measurement precision(alignment precision) required is different for each measurement axisdirection, there may be cases in which the optimum measurementconditions are different for each measurement object (mark). However, inmeasurement methods of the conventional art, measurements are performedunder a single set of measurement conditions when performing a series ofmeasurement processing operations, so that measurements may not havebeen performed under optimum conditions for each of the measurementobjects (marks). If measurement conditions were to be modified for eachmeasurement object, such problems as a considerable worsening ofthroughput, or adverse effects on the measurement precision accompanyingfluctuations in the baseline value, or similar would result, and someasurement under such optimum conditions have in effect not beenpossible.

-   Patent Reference 1: Japanese Unexamined Patent Application, First    Publication No. 2002-170757-   Patent Reference 2: Japanese Unexamined Patent Application, First    Publication No. H09-134863

DISCLOSURE OF INVENTION

According to a first aspect of the invention, a measurement method isprovided which is a measurement method of using a measurement system tomeasure a plurality of first marks and a plurality of second marksdifferent from the first marks as measurement objects formed on theprescribed substrate, and comprises a first process of setting ameasurement condition for the measurement system as a first conditionwhen measuring the plurality of first marks among the marks which arethe measurement objects on the prescribed substrate (S211, S411); asecond process, after measuring all of the first marks on the prescribedsubstrate under the first condition (S212 to S215, S413 to S416), ofswitching the measurement condition from the first condition and settinga second condition (S221, S421); and, a third process of measuring allof the second marks among the marks which are the measurement objects onthe prescribed substrate, under the second condition (S222 to S225, S423to S426).

According to a second aspect of the invention, a measurement method isprovided which is a measurement method of using a measurement system tomeasure a plurality of first marks and a plurality of second marksdifferent from the first marks as measurement objects formed on theprescribed substrate, and comprises a first process of setting ameasurement condition for the measurement system to a first conditionwhen measuring the first marks on the prescribed substrate (S311, S411);a second process of setting the measurement condition for themeasurement system to a second condition, different from the firstcondition, when measuring the second marks on the prescribed substrate(S321, S421); and a third process of measuring, for both the firstcondition and for the second condition, a baseline value, which is aninterval between a reference position for measurements using themeasurement system and a reference position which specifies the positionwhen performing processing in a processing system to perform desiredprocessing of the substrate (S312, S322, S412, S422).

According to a third aspect of the invention, a measurement method isprovided which is a measurement method of using a measurement system,comprising an illumination optical system which irradiates a pluralityof first marks and a plurality of second marks different from the firstmarks as measurement objects formed on the prescribed substrate, with anilluminating beam and a light-receiving optical system which receivesthe light beam from the marks, to measure the first and second marks,and wherein, as a measurement condition which can be modified whenmeasuring the marks, the measurement system comprises at least one amonga light quantity of the illumination beam, NA or σ of the illuminationoptical system, an insertion into or retraction from the light-receivingoptical system of a phase-imparting member which imparts a prescribedphase difference to the diffraction beam of a prescribed order arisingfrom the marks, and a signal processing condition when processing aphotoelectric converted signal obtained upon receiving the beam arisingfrom the marks; and wherein, when measuring the first marks on theprescribed substrate, the measurement condition of the measurementsystem are set to a first condition (S111), and when measuring thesecond marks on the prescribed substrate, the measurement condition ofthe measurement system is a set to second condition different from thefirst condition (S113).

According to a fourth aspect of the invention, an exposure method isprovided which is an exposure method for transferring a pattern formedon a mask onto a substrate, and which comprises a process of using themeasurement method according to any one of the above-described firstthrough third aspects to measure the positions of marks formed on themask or substrate, and based on the measurement results, of performingpositioning of the mask or of the substrate.

According to a fifth aspect of the invention, a measurement apparatus isprovided which enables measurement of measurement objects on a body bymeans of the measurement method according to any one of theabove-described first through third aspects.

According to a sixth aspect of the invention, a measurement apparatus isprovided which is a measurement apparatus to measure a plurality offirst marks and a plurality of second marks different from the firstmarks as measurement objects formed on a prescribed substrate, and whichhas a condition setting means for setting a measurement condition forthe measurement apparatus to a first condition when measuring theplurality of first marks among the marks which are the measurementobjects on the prescribed substrate and for setting the measurementcondition to a second condition different from the first condition whenmeasuring the plurality of second marks, and a control means forcontrolling the condition setting means so as to switch the measurementcondition from the first condition to set the second condition aftermeasuring all of the first marks on the prescribed substrate under thefirst condition.

According to a seventh aspect of the invention, a measurement apparatusis provided which is a measurement apparatus to measure a plurality offirst marks and a plurality of second marks different from the firstmarks as measurement objects formed on a prescribed substrate, and whichhas a condition setting means for setting a measurement condition forthe measurement apparatus to a first condition when measuring theplurality of first marks among the marks which are the measurementobjects on the prescribed substrate and for setting the measurementcondition to a second condition different from the first condition whenmeasuring the plurality of second marks, and a retention apparatus(memory 305) which retains for each of the conditions which are set abaseline value, which is the interval between a reference position formeasurements using the measurement apparatus and a reference positionwhich specifies the position when performing processing in a processingapparatus to perform desired processing of the substrate.

According to an eighth aspect of the invention, a measurement apparatusis provided which is a measurement apparatus to measure a plurality offirst marks and a plurality of second marks different from the firstmarks as measurement objects formed on a prescribed substrate, whichcomprises an illumination optical system to irradiate the marks with anilluminating beam and a light receiving optical system which receivesthe beam from the marks, and which has condition setting means forsetting, as the measurement condition of the measurement apparatus whichcan be modified when measuring the marks, at least one among the lightquantity of the illumination beam, the NA or σ of the illuminationoptical system, the insertion into or retraction from thelight-receiving optical system of a phase-imparting member which impartsa prescribed phase difference to the diffraction beam of a prescribedorder arising from the marks, and the signal processing condition whenprocessing photoelectric converted signals obtained upon receiving thebeam arising from the marks, to a first condition as measurementcondition of the measurement apparatus when measuring the plurality offirst marks among the marks which are the measurement objects on theprescribed substrate, and for setting the measurement condition to asecond condition different from the first condition when measuring theplurality of second marks.

According to a ninth aspect of the invention, an exposure apparatus isprovided which is an exposure apparatus for transferring a patternformed on a mask onto a substrate, which has a positioning apparatususing, for either the mask or the substrate, the measurement apparatusaccording to any one among the above-described fifth through eighthaspects to measure the positions of marks formed on the mask orsubstrate, and which performs positioning of the mask or substrate basedon the measurement results.

By means of a measurement method or measurement apparatus of thisinvention, the optimum measurement condition can be set for eachmeasurement object and measurements performed without causing areduction in measurement throughput, and consequently measurements canbe performed rapidly and with high precision. And, by means of anexposure method or exposure apparatus of this invention, a measurementmethod or measurement apparatus of this invention is used to positionthe wafer or reticle, so that exposure processing can be performedrapidly and with high precision.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the configuration of the exposure apparatus of an aspect ofthe invention;

FIG. 2 shows the configuration of an alignment sensor in the exposureapparatus shown in FIG. 1;

FIG. 3A is a diagram used to explain the illumination aperture diaphragmof the alignment sensor shown in FIG. 2;

FIG. 3B is a side view used to explain the phase difference plate of thealignment sensor shown in FIG. 2;

FIG. 3C is a bottom view used to explain the phase difference plate ofthe alignment sensor shown in FIG. 2;

FIG. 4 shows the configuration of the main control system of theexposure apparatus shown in FIG. 1;

FIG. 5A shows an image of wafer marks captured by the image capturedevice of the alignment sensor shown in FIG. 2;

FIG. 5B shows a signal waveform when the image of wafer marks shown inFIG. 5A is captured by the image capture device of the alignment sensorshown in FIG. 2;

FIG. 6 is a diagram used to explain the arrangement of shots on thewafer, and the placement of sample shots and alignment marks;

FIG. 7 shows the flow of measurement processing in which measurementconditions are changed for each axis direction;

FIG. 8 shows the flow of processing to change the measurement conditionsfor each axis direction, and to perform measurements of mark positionscontinuously for each axis direction;

FIG. 9 shows the flow of processing to measure the baseline for eachaxis direction; and,

FIG. 10 shows the flow of processing to perform repeated measurements ofthe baseline each time the measurement conditions are modified.

BEST MODE FOR CARRYING OUT THE INVENTION

The exposure apparatus of an embodiment of the invention is describedreferring to FIG. 1 to FIG. 10. FIG. 1 shows in summary theconfiguration of the exposure apparatus 100 of this embodiment. In thefollowing description, the constituent elements and the positionalrelations thereof are described based on an XYZ orthogonal coordinatesystem such as that shown in FIG. 1. In this XYZ orthogonal coordinatesystem, the X axis and Z axis are set parallel to the plane of thepaper, and the Y axis is set perpendicular to the plane of the paper. Inactual space, the XY plane is a plane parallel to the horizontal plane,and the Z axis direction is the vertical direction. In the exposureapparatus 100 shown in FIG. 1, the exposure light EL radiated from theillumination optical system, not shown, passes through the condenserlens 101 to irradiate the pattern area PA formed on the reticle R with auniform illuminance distribution. As the exposure light EL, for example,the g line (wavelength 436 nm), i line (wavelength 365 nm), KrF excimerlaser beam (wavelength 248 nm), ArF excimer laser beam (wavelength 193nm), or F₂ laser beam (wavelength 157 nm), or similar is used.

The reticle R is placed on the reticle stage 103. The reticle stage 103is installed so as to enable fine movement along the direction of theoptical axis AX of the projection optical system PL by the motor 102,and moreover can move in two dimensions and can undergo fine rotation inthe plane perpendicular to the optical axis AX. A movement mirror 105which reflects a laser beam from a laser interferometer 104 is fixed toan edge portion of the reticle stage 103, and the two-dimensionalposition of the reticle stage 103 is continuously detected, with aresolution of for example approximately 0.01 μm, by the laserinterferometer 104.

The reticle alignment systems 106A and 106B (hereafter collectivelycalled the “reticle alignment system 106”) are positioned above thereticle R. The reticle alignment system 106 detects at least twocross-shaped alignment marks formed in the vicinity of the periphery ofthe reticle R. Through fine movement of the reticle stage 103 based onmeasurement signals from the reticle alignment system 106, the reticle Ris positioned such that the center point of the pattern area PAcoincides with the optical axis AX of the projection optical system PL.

The exposure light EL passing through the pattern area PA of the reticleR passes through for example both sides (or one side) of the telecentricprojection optical system PL and is projected onto each shot area on thewafer (substrate) W. The projection optical system PL is correctedoptimally for aberration for the wavelength of the exposure light EL,and at this wavelength, the reticle R and wafer W are mutuallyconjugate. The projection optical system PL has a plurality of opticalelements such as lenses; as the lens material of these optical elements,quartz, fluorite, or another optical material is selected according tothe wavelength of the exposure light EL.

The wafer W is mounted on the wafer stage 109 via a wafer holder 108. Areference plate 110 is provided on the wafer holder 108. On thisreference plate 110 are formed wafer fiducial marks (wafer referencemarks) used in baseline measurements and similar. The surface of thereference plate 110 is set so as to be the same height as the surface ofthe wafer W.

The wafer stage 109 comprises an XY stage which positions the wafer W intwo dimensions within the plane perpendicular to the optical axis AX ofthe projection optical system PL; a Z stage which positions the wafer Win the direction parallel to the optical axis AX of the projectionoptical system PL (the Z direction); a stage for fine rotation of thewafer W; a stage to adjust the inclination of the wafer W relative tothe XY plane by changing the angle with respect to the Z axis; andsimilar. An L-shape movement mirror 111 is mounted on one end of theupper face of the wafer stage 109, and a laser interferometer 112 ispositioned in a position opposing the mirror face of the movement mirror111. In FIG. 1, the diagram is simplified, but the movement mirror 111comprises a plane mirror having a reflecting face perpendicular to the Xaxis and a plane mirror having a reflecting face perpendicular to the Yaxis.

The laser interferometer 112 comprises two X-axis laser interferometerswhich emit laser beams along the X axis to irradiate the movement mirror111 and a Y-axis laser interferometer which emits a laser beam along theY axis to irradiate the movement mirror 111; the X coordinate and Ycoordinate of the wafer stage 109 are measured by means of one X-axislaser interferometer and one Y-axis laser interferometer. In addition,the rotation angle in the XY plane of the wafer stage 109 is measuredusing the difference in the measurement values of the two X-axis laserinterferometers.

The two-dimensional coordinates of the wafer stage 109 are constantlydetected by the laser interferometer 112 with a resolution of forexample approximately 0.01 μm, and the stage coordinate system(stationary coordinate system) (x,y) of the wafer stage 109 isdetermined from the coordinates in the X-axis direction and Y-axisdirection. That is, the coordinate values of the wafer stage 109measured by the laser interferometer 112 are coordinate values in thestage coordinate system (x,y).

Position measurement signals PDS indicating the X coordinate, Ycoordinate, and rotation angle measured by the laser interferometer 112are output to the main control system 300. The main control system 300generates control signals to control the position of the wafer stage 109based on the position measurement signals PDS thus supplied, and outputsthe generated signals to the motor 113. The main control system 300, bycontrolling whether or not exposure light is emitted from the lightsource, not shown, and by controlling the intensity of the exposurelight when exposure light is emitted, controls the exposure lightpassing through the condenser lens 101 and the projection optical systemPL.

The exposure apparatus 100 comprises, on the side of the projectionoptical system PL, an alignment optical system 200 (hereafter called analignment sensor 200) employing the off-axis FIA (Field Image Alignment)method (image capture method). The alignment sensor 200 is described indetail referring to FIG. 2. FIG. 2 shows in summary the configuration ofthe alignment sensor 200.

In the alignment sensor 200, broad-band illumination light (broad-bandlight) emitted from a halogen lamp or other light source 241 passesthrough the condenser lens 242 and wavelength selection mechanism 243,and is incident on the illumination field diaphragm 244.

The wavelength selection mechanism 243 is a mechanism which causes abeam in a wavelength region to which photoresist applied to the wafer Wis insensitive, and only a beam in a wavelength region suitable fordetection of the marks or similar which are the detection objects(alignment objects), to be passed. The wavelength selection mechanism243 has, for example, a plurality of filters to extract light ofmutually different wavelengths, and a filter driving unit that puts oneamong the plurality of filters on the optical path of the broad-bandlight emitted from the light source 241. In this embodiment, thewavelength selection mechanism 243 comprises four filters, whichrespectively pass a beam of wavelength 530 to 620 nm (green light), abeam of wavelength 620 to 710 nm (orange light), a beam of wavelength710 to 800 nm (red light), and a beam of wavelength 530 to 800 nm (whitelight). It is preferable that the filters used in wavelength selectionbe positioned at positions which are conjugate with the light source241, and at which irregular coloring does not readily occur. Filters arenot limited to the filter types which pass prescribed wavelength regionsas described above, and a plurality of filter types which cut outprescribed wavelength regions may be used in combination to extract andpass only desired wavelengths.

Illumination light DL which has passed the transmission portion of theillumination field diaphragm 244 passes through the relay lens 245 andis incident on the illumination aperture diaphragm 246 (263).Furthermore, the illumination light DL passes through a beam splitter247 and objective lens 248, and illuminates an area comprising marks WMwhich are position detection objects of the wafer W or another desiredillumination area. The illumination field diaphragm 244 is effectivelyconjugate (in a focusing relation) with the surface of the wafer W (thewafer marks WM), and the illumination area on the wafer W can be limitedaccording to the shape and size of the transmission portion of theillumination field diaphragm 244.

The illumination aperture diaphragm 246 (263) is positioned in the plane(called the illumination system pupil plane) which is in an opticalFourier transform relation, via the objective lens 248 and beam splitter247, with the wafer surface (wafer marks WM). As the illuminationaperture diaphragm, a configuration is employed enabling selection of anillumination aperture diaphragm 246 having a normally round transmissionportion, and an illumination aperture diaphragm 263 having a ring-shapedtransmission portion 263 a such as shown in FIG. 3A. When a normalillumination state (so-called normal illumination) of the marks is usedto perform alignment (mark) measurement, the illumination aperturediaphragm 246 is positioned on the illumination optical path, and whenso-called modified illumination (or ring-shaped illumination as inclinedillumination) is used to perform mark measurements, the illuminationaperture diaphragm 263 is positioned on the illumination optical axis.Which of the aperture diaphragms 246 and 263 is selected is determinedaccording to the step amount and fineness of the wafer marks WM, theline width, and similar. This is well-known as described in JapaneseUnexamined Patent Application, First Publication No. H08-306609, and soa detailed description is here omitted. An illumination aperturediaphragm 263 such as that shown in FIG. 3A can also be used togetherwith a phase difference plate 263 as described below, and through thisuse, the alignment sensor 200 can be made to function as a phasedifference microscope-type sensor. In this case, the ring-shapetransmission portion 263 a of the illumination aperture diaphragm 263 isset such that the image thereof enters into the phase differenceimparting portion 264 a of the ring shape on the phase difference plate264, described below.

The beam reflected by the illumination area comprising the wafer marksWM on the wafer W is incident on the imaging aperture diaphragm 249having a circular aperture portion. The diaphragm is positioned in theplane (called the imaging system pupil plane) H2 which is in an opticalFourier transform relation with the surface of the wafer W via theobjective lens 248 and beam splitter 247. As this imaging aperturediaphragm 249, a well-known imaging aperture diaphragm comprising ablocking portion with a ring blocking shape such as that of JapaneseUnexamined Patent Application, First Publication No. H08-306609 may beconfigured to enable insertion in the imaging optical path, to enabledark field detection in combination with the above-describedillumination aperture diaphragm 263. It is preferable that, if the wafermarks are low step marks, dark field detection be used, and if the marksare high step marks, the imaging diaphragm be retracted from the opticalpath so that the bright field detection method is used.

As described above, when adopting an illumination aperture diaphragm 263such as shown in FIG. 3A as the illumination aperture diaphragm, thephase difference plate 264 is inserted and positioned in the reducing(projection) optical path in proximity to the imaging aperture diaphragm249, and the beam reflected from the wafer W is made incident on thephase difference plate 264 together with the imaging aperture diaphragm249. As shown in the side view of FIG. 3B and in the bottom view of FIG.3C, phase difference plate 264 comprises a ring-shaped phase differenceimparting portion 264 a affixed to the bottom face of a circular glasssubstrate; when used, the diaphragm is set such that, as describedabove, an image of the ring-shaped transmission portion 263 a of theillumination aperture diaphragm 263 enters into the ring-shaped phasedifference imparting portion 264 a on the phase difference plate 264.

In this embodiment, the phase difference plate 264 is set so as toimpart a phase difference of +π/2 (rad) or −π/2 (rad) between theimaging beam passing through the phase difference imparting portion 264a and the imaging beam passing through portions other than this. To thisend, if the wavelength or central wavelength of the imaging beam is λ,then the phase difference imparting portion 264 a (or portions otherthan this) should be formed as a thin film of refractive index n andthickness d so as to satisfy the equation (n−1)d=λ/4.

By applying a phase difference microscope-type optical system to thealignment sensor 200 using an illumination aperture diaphragm 263 suchas shown in FIG. 3A and a phase difference plate 264 such as shown inFIG. 3B and FIG. 3C, high-contrast detection images can be obtained evenfor extremely low step wafer marks WM. The phase difference impartingportion 264 a shown in FIG. 3B and FIG. 3C may also be provided with alight-reducing action to further attenuate the transmitted beam. Thatis, a metal thin film or other light-absorbing member may be added tothe phase difference imparting portion 264 a.

The beam transmitted by the imaging aperture diaphragm 249 is condensedby the imaging lens 250, passes through the beam splitter 251, and formsan image of the wafer marks WM on the index plate 252. On the indexplate 252 are formed index marks 252 a and 252 b. Furthermore, an indexplate illumination system comprises a light-emitting diode (LED) orother light source 255, condenser lens 256, index illumination fielddiaphragm 257, lens 258, and similar, and is set such that theillumination light from this index plate illumination system passesthrough the beam splitter 251 and illuminates only partial areascomprising the index marks 252 a and 252 b. The shape of thetransmission portion of the illumination field diaphragm 244 is set suchthat the partial areas comprising the index marks 252 a and 252 b arenot illuminated, and light is blocked. Hence images of the wafer marksWM are not formed in superposition on the index marks 252 a and 252 b.

The images of wafer marks WM formed on the index plate 252, and the beamfrom the index marks 252 a and 252 b, are condensed on the CCD or otherimage capture device 254 via the relay lens 253. As a result, images ofwafer marks WM and images of the index marks 252 a and 252 b are formedon the image-capture face of the image capture device 254. Image capturesignals SV from the image capture device 254 are output to the maincontrol system 300, and in the main control system 300 positioninformation for the marks is computed.

Next, the configuration of the main control system 300 is described.FIG. 4 is a block diagram showing the internal configuration of the maincontrol system 300 and constituent elements related thereto. In FIG. 4,constituent elements which are the same as elements portions in FIG. 1are assigned the same symbols. As shown in FIG. 4, the main controlsystem 300 has a FIA computation unit 301, waveform data storage device302, alignment data storage portion 303, computation unit 304, storageportion 305, shot map data portion 306, system controller 307, waferstage controller 308, reticle stage controller 309, main focusing system320, and alignment focusing system 330.

The waveform data storage device 302 is a circuit which stores imagecapture signals (waveform data) SV detected by the alignment sensor 200and supplied via the FIA computation unit 301, as well as output signalsfrom the main focusing system 320 and alignment focusing system 330. Thewaveform data storage device 302 stores signal waveforms for variousalignment marks provided on the wafer W and for wafer fiducial marks WFMformed on the reference plate 110 provided on the wafer holder 108. Onthe wafer W (FIG. 6) described below, one-dimensional X marks and Ymarks are formed separately accompanying each shot area. In such cases,the waveform data for the X marks and Y marks is stored separately inthe waveform data storage device 302. No constraints are imposed on themark shape, but the marks may be marks of a shape enablingsimultaneously measurement in two dimensions.

The FIA computation unit 301 reads waveform data from the waveform datastorage device 302 as necessary, determines position information, thatis, coordinate positions in the stage coordinate system (x,y) for eachmark (waveform data), and outputs the position information thusdetermined to the alignment data storage portion 303. The FIAcomputation unit 301 performs processing to generate waveform data or todetect coordinate positions from waveform data and other processingaccording to a prescribed signal processing algorithm specified by thesystem controller 307.

One example of processing to detect mark positions in the FIAcomputation unit 301 is described referring to FIG. 5. FIG. 5A showsmarks Mx1 for position detect in the X axis direction, captured by theimage capture device 254 (see FIG. 2) of the alignment sensor 200; FIG.5B shows the image capture signal waveform obtained. As shown in FIG.5A, a plurality of marks Mx1 which are straight patterns, and indexmarks FM1, FM2 formed on the index plate 252 (see FIG. 2) so as toenclose the marks Mx1, are positioned within the image capture field VSAof the image capture device 254. The image capture device 254electrically scans the images of these marks Mx1 and index marks FM1,FM2 along the horizontal scan line VL. At this time, because a singlescan line alone is disadvantageous from the standpoint of the SN ratio,it is desirable that the image capture signal levels for a plurality ofhorizontal scan lines within the image capture field VSA be added andaveraged for each pixel in the horizontal direction. As a result, animage capture signal is obtained with depressions corresponding to theindex marks FM1 and FM2 on both sides, as shown in FIG. 5B, and theimage capture signal is stored in the waveform data storage device 302via the FIA computation unit 301.

The FIA computation unit 301 detects the depressions in this imagecapture image at slice level SL2, and determines the center positions ofthe pixels of both depressions. Then, the reference position x₀ isdetermined as the center of these two center positions, when the indexmarks FM1 and FM2 are used as reference. Instead of determining thecenter positions of the index marks FM1, FM2, the right-edge position ofthe index mark FM1 and the left-edge position of the index mark FM2 maybe used to determine the reference position x₀.

As shown in FIG. 5B, the waveform for the portion corresponding to themarks Mx1 in the image capture signal has depressions at positionscorresponding to the left edges and right edges of each of the straightpatterns. The FIA computation unit 301 detects the depressionscorresponding to the marks Mx1 of this image capture signal at slicelevel SL1, and after determining the center positions of each straightpattern, averages the center positions to compute the measured positionx_(c) of the marks Mx1. Then, the difference Δx (=x₀−x_(c)) is computedfrom the previously determined reference position x₀ and the measuredposition x_(c) of the marks Mx1. Then, the value obtained by adding thecomputed difference Δx to the coordinate position of the wafer stage 109at the time of positioning of the wafer marks Mx1 in the image capturearea VSA of FIG. 5A is supplied, as the mark position information, tothe alignment data storage portion 303.

In the FIA computation unit 301 which performs this processing, thereare, as selectable signal processing conditions (alignment measurementconditions), the waveform analysis algorithm, slice level SL1,processing gate width GX in FIG. 5B (the pixel center position and widthof Gx), and similar. Furthermore, as the waveform analysis algorithm,when determining the center positions of each of the straight patterns,among the slope portions BS_(1L), BS_(2L) and BS_(1R), BS_(2R)corresponding to the left edge and right edge of the straight patternsas shown in FIG. 5B, there are (1) a mode in which the outside slopeportions BS_(1L) and BS_(2R) alone are used, (2) a mode in which theinside slope portions BS_(1R) and BS_(2L) alone are used, and (3) a modein which the outside slope portions BS_(1L) and BS_(2R) and the insideslope portions BS_(1R) and BS_(2L) are used, as for example disclosed inJapanese Unexamined Patent Application, First Publication No. H04-65603.

The alignment data storage portion 303 stores the positions of each markdetected by the FIA computation unit 301. Moreover, when wafer fiducialmarks WFM input from the reticle alignment system 106 are observed usingthe reticle alignment system 106, the coordinate positions (positioninformation in the coordinate system of the projection optical systemPL) are stored via the system controller 107. Each of the coordinatepositions stored in the alignment data storage portion 303 is suppliedto the computation unit 304, and is supplied to EGA processing, baselinemeasurement processing and similar.

Position information stored in the alignment data storage portion 303 isdirectly supplied as needed to the system controller 307. For example,in the case of multistage processing to perform fine measurements afterpositioning of the wafer W based on the results of rough measurements,in cases in which marks formed on the wafer W include marks to measureposition information in the X axis direction and separate marks tomeasure position information in the Y axis direction, and in cases inwhich the wafer W is moved based on the results of measurements of marksto measure position information in the X axis direction, and then marksfor measurement of position information in the Y axis direction aremeasured, the position information stored in the alignment data storageportion 303 is directly supplied to the system controller 307.

The shot map data storage portion 306 stores design array coordinatevalues in the coordinate system (x,y) on the wafer W of marks belongingto each shot area on the wafer. These design array coordinate values aresupplied to the computation unit 304 and system controller 307.

The computation unit 304 detects EGA parameters. That is, conversionparameters are determined in order to determine array coordinate valuesfor computation in the stage coordinate system (x,y) from the designarray coordinate values in the coordinate system (x,y) on the wafer Wusing the least-squares method, based on the measured coordinate valuesand design coordinate values; these conversion parameters are stored inthe storage portion 305.

The computation unit 304 also computes the distance between the opticalaxis of the alignment sensor 200 and the optical axis AX of theprojection optical system PL, that is, the baseline value, by detectingthe distance between the position coordinates of wafer fiducial marksWFM measured by the alignment sensor 200 and stored in the alignmentdata storage portion 303 and the position coordinates of the waferfiducial marks WFM measured by the reticle alignment system 106 via theprojection optical system PL. In this embodiment, the baseline value ismeasured separately for each alignment measurement condition set (used)at the time of mark measurements. Furthermore, each detected baselinevalue is stored in the storage portion 305 in association with thepreset alignment measurement conditions.

The system controller 307 determines the array coordinate values forcomputation in the stage coordinate system (x,y) from the design arraycoordinate values in the wafer W coordinate system (x,y), using the EGAparameters determined by the computation unit 304 and stored in thestorage portion 305. The system controller 307 then drives the waferstage 109 via the motor 113, while monitoring values measured by thelaser interferometer 112 via the wafer stage controller 308, positionseach shot area on the wafer W, and performs exposure of each shot area.

Moreover, the system controller 307 adjusts the position of the reticleR by driving the reticle stage 103 via the motor 102, while monitoringvalues measured by the laser interferometer 104 via the reticle stagecontroller 309.

Next, processing relating to this invention in an exposure apparatus 100configured as described above is described. The exposure apparatus 100precisely detects the positions of the wafer W set on the wafer stage109 (on the wafer holder 108) and of a plurality of shot areas providedon the wafer W, performs precise positioning (alignment) of these atdesired positions, and projects an image of a pattern formed on thereticle R onto each shot area to perform exposure. Here, processing tomeasure the positions of marks formed on the wafer at the time of thisalignment processing, and processing to detect the baseline value inrelation to this, are described for first through fourth specificprocessing examples. All of the processing described below isaccomplished by having the main control system 300 of the exposureapparatus 100 perform operations according to a control program set inthe main control system 300, by which means each of the portions of theexposure apparatus 100 is controlled.

First, the array of shot areas on the wafer W to be exposed in theexposure apparatus 100, and the alignment marks formed on the wafer W,are described referring to FIG. 6. FIG. 6 shows an array of shot areason the wafer W, and the arrangement of sample shots and alignment marks.As shown in FIG. 6, the shot areas ES1, ES2, . . . , ESN are provided onthe wafer W regularly along the axes of the coordinate system (x,y) seton the wafer W. In each shot area ESi (i=1 to N), the layers of patternsformed up to this process are layered. Furthermore, each shot area ESiis delimited by street-lines of prescribed width in the x direction andy direction.

On this wafer W, marks (X marks) to measure the positions in the X-axisdirection of each of the shot areas ESi, and marks (Y marks) to measurethe positions in the Y-axis direction, are formed separately. That is, Xmarks Mxi to perform alignment in the X-axis direction are formed in thestreet-line areas extending in the x direction which are in contact witheach shot area ESi, and Y marks Myi to perform alignment in the Y-axisdirection are formed in the street-line areas extending in the ydirection which are in contact with each shot area ESi. In thisembodiment, the marks Mxi and Myi are marks arranged in a plurality ofstraight patterns with prescribed pitch in the x direction and ydirection respectively, as shown in FIG. 5.

On the wafer W, it is assumed that the measurement conditions whenmeasuring marks using the alignment sensor 200 are different for X marksand for Y marks. Such a state may occur for various reasons; but in thisembodiment, it is assumed as one example that, as described for examplein Japanese Patent No. 2591746 and Japanese Unexamined PatentApplication, First Publication No. H07-249558, when it is necessary toperform alignment spanning a plurality of layers formed on a substrate(multiple layers) in order to superpose and expose the next layer,alignment in the Y direction is for example performed relative to theimmediately preceding layer (as reference), and alignment in the Xdirection is performed relative to the layer preceding the former layer(as reference). More specifically, Y-direction positioning is performedfor a pattern (marks) formed in the uppermost layer among the patternlayers previously formed on the wafer W, and positioning in the Xdirection is performed relative to a pattern (marks) formed in the layerbelow the uppermost layer. Hence when X marks are observed duringalignment measurements, the X marks formed in the layer below theuppermost layer are observed via the uppermost layer in which the Ymarks are formed on the wafer W. Consequently, alignment measurementconditions to perform appropriate measurements of the X marks(illumination conditions, optical conditions, signal processingalgorithm, and similar) differ from the alignment measurement conditionsto appropriately measure the Y marks.

In FIG. 6, shot areas SA1 to SA4 which are diagonally shaded representsample shot areas when EGA is applied to the wafer W, and will bereferenced when subsequently describing various processing examples.

Below, first through fourth processing examples are described asprocessing of this invention in an exposure apparatus 100, when such awafer W is the object of processing.

First Processing Example

As the first processing example for the exposure apparatus 100,processing is described, referring to FIG. 7, in which the positions ofeach of the shot areas on the above-described wafer W are detected usingthe EGA method. To this end, first, a prescribed number (three or more)of shot areas are selected as sample shots from among the shot areas ES1to ESN on the wafer W, and the coordinate positions in the stagecoordinate system (x,y) of each sample shot are measured. In thisembodiment, for example, four shot areas SA1 to SA4, indicated bydiagonal shading in FIG. 6, are selected. By then measuring thepositions of the X marks Mx1 to Mx4 and the Y marks My1 to My4 formed incontact with each of these sample shot areas SA1 to SA4, the positionsof the sample shot areas SA1 to SA4 are measured.

A feature of this first processing example is the fact that marks (Xmarks and Y marks) are measured for each shot in order, and that themeasurement conditions are switched upon each shot measurement (formeasurement of each mark). First, the system controller 307 of the maincontrol system 300 moves the wafer stage 109 via the wafer stagecontroller 308 based on a shot map stored in the shot map data portion306, and positions the Y mark My1 for position measurement in the Y axisdirection, provided for the sample shot SA1, within the measurementfield of the alignment sensor 200. Furthermore, the system controller307 executes control of settings of each of the portions within thealignment sensor 200 and main control system 300 so as to set thealignment measurement conditions (first conditions) which are optimalfor observing and capturing an image of the Y mark My1 and measuring theposition thereof (step S111). Specifically, the Y mark My1 is forexample formed on the uppermost layer of the pattern layer formed on thewafer W, and so there is no particular need to limit the wavelength ofthe observation light (illumination light) for observation of the mark,and observation may be performed using broad-band white light. Hence thesystem controller 307 controls the wavelength selection mechanism 243such that the filter to pass a beam with wavelengths from 530 to 800 nm(white light) is selected in the wavelength selection mechanism 243 ofthe alignment sensor 200.

As alignment measurement conditions other than the above-describedalignment light wavelength, the main control system 300 (systemcontroller 307) controls the illumination field diaphragm 244,illumination aperture diaphragm 246, imaging aperture diaphragm 249, andindex illumination field diaphragm 257, and controls the optical systemnumerical aperture N.A., σ, and illumination light quantity (lightsources 241 and 255) of the alignment sensor 200 and similar.Furthermore, the main control system 300 (system controller 307) alsoexecutes control as necessary (as alignment measurement conditions(first conditions)) to switch and position an illumination aperturediaphragm placed in a stage beyond the relay lens 245 between theillumination aperture diaphragm 246 having a normal circulartransmission portion and the illumination aperture diaphragm 263 havinga ring-shaped transmission portion 263 a as shown in FIG. 3A(modification of illumination conditions), or to insert or remove adiaphragm (not shown) having a ring-shaped blocking portion (a blockingportion which blocks 0th order diffracted light from marks) in place ofthe diaphragm 249 as the above-described imaging aperture diaphragm soas to switch between dark-field and bright-field detection methods, orto insert and position a phase difference plate 264 at a position inproximity to the imaging aperture diaphragm 249 beyond the imagingaperture diaphragm 249, causing the alignment sensor 200 to function asa phase-difference microscope type sensor.

Furthermore, the system controller 307 controls the FIA computation unit301 so as to select, as the signal processing algorithm (one alignmentmeasurement condition) used by the FIA computation unit 301 of the maincontrol system 300, the optimum algorithm for measurement of the Y markMy1.

The Y mark My1 which is the measurement object is positioned within themeasurement field, and when the alignment measurement conditions are setto the conditions which are optimum for measurement of the Y mark My1(the first conditions), measurement of the Y mark My1 is performed (stepS112). That is, illumination light emitted from the light source 241 ismade incident on the area for detection comprising the mark My1 which isthe measurement object, and light reflected from the area for detectionis converted into image capture signals by the image capture device 254.The image capture signals of the captured Y mark My1 image aretransferred from the alignment sensor 200 to the main control system300, and are stored in the waveform data storage device 302 of the maincontrol system 300.

When the waveform data has been stored in the waveform data storagedevice 302, the FIA computation unit 301 reads this data, and performssignal processing according to the signal processing conditions set instep S111, that is, using the prescribed algorithm, computationprocessing, slice level and similar which have been selected, to detectmarks from the captured image and determine their positions. When the Ymark My1 is detected from the captured image signal, the positioncoordinates are stored in the alignment data storage portion 303, andmeasurement of the coordinate (Y coordinate) of the Y mark My1 for thefirst sample shot area SA1 is completed.

When coordinate measurement of the Y mark My1 for the first sample shotarea SA1 is completed, next coordinate measurement is performed for theX mark Mx1 for the first sample shot area SA1. First, the systemcontroller 307 of the main control system 300 moves the wafer stage 109via the wafer stage controller 308 based on the shot map stored in theshot map data portion 306, and based on the relative design values ofthe coordinates of the Y mark My1 which is the current measurementobject and of the coordinates of the X mark Mx1 which is the nextmeasurement object as well as on the position information of the Y markMy1 currently being measured, and causes the X mark Mx1 for positionmeasurement in the X axis direction, provided for the sample shot SA1,to be positioned within the measurement field of the alignment sensor200.

The system controller 307 controls the settings of each portion withinthe alignment sensor 200 and main control system 300 so as to becomealignment measurement conditions (second conditions, different from theabove first conditions) suitable for observation, image capture, andmeasurement of the position of the X mark Mx1. Specifically, forexample, the X mark Mx1 is a mark formed in the layer which is one layerbelow the uppermost layer of the pattern layer formed on the wafer W, asdescribed above, and so, as observation light for appropriateobservation thereof, use of observation light (illumination light) witha high transmissivity for the material comprised by the uppermost layeris preferable. For example, if this observation light is red light, thenthe system controller 307 controls the wavelength selection mechanism243 so as to select a filter which transmits a beam of wavelength 710 to800 nm (red light) in the wavelength selection mechanism 243 of thealignment sensor 200.

Furthermore, and similarly to the above description for the case of theY mark My1, the main control system 300 (system controller 307) controlssettings as necessary of the light sources 241 and 255, control of thediaphragms 244, 246, 249 and 257, selection of the illumination aperturediaphragm, positioning of the phase difference plate, signal processingconditions in the FIA computation unit 301 of the main control system300, and similar, as alignment measurement conditions (secondconditions), such that measurement conditions for measurement of the Xmark Mx1 are optimum.

When the X mark Mx1 which is the measurement object is positioned withinthe measurement field, and the measurement conditions are set to theoptimum conditions for measurement of the X mark Mx1, measurement of theX mark Mx1 is performed (step S114). That is, red illumination lightemitted from the light source 241 is made incident on the detection areacomprising the X mark Mx1 which is the measurement object, and lightreflected from the detection area is converted into an image capturesignal by the image capture device 254. The signal for the capturedimage of the X mark Mx1 is transferred from the alignment sensor 200 tothe main control system 300, and is stored in the waveform data storagedevice 302 of the main control system 300.

When the waveform data is stored in the waveform data storage device302, the FIA computation unit 301 reads this data, performs signalprocessing according to the signal processing conditions set in stepS113, that is, using the prescribed algorithm, computation processing,slice level and similar which have been selected, and detects the markfrom the captured image. When the X mark Mx1 is detected from the imagecapture signal, the position coordinates are stored in the alignmentdata storage portion 303, and measurement of the first mark X coordinateis completed.

When measurement of the Y mark My1 and X mark Mx1 for the first sampleshot is completed, position measurements are similar performed of the Ymarks and X marks for the second through fourth sample shots. That is,for example, the wavelength band of the illumination light, as onealignment measurement condition, is switched to broad-band white light(broad-band illumination), and other parameters are similarly set tomeasurement conditions (first conditions) appropriate for measurement ofY marks (step S121), and position measurement of the Y mark My2 for thesecond sample shot SA2 is performed (step S122). Next, for example thewavelength band of the illumination light, as one alignment measurementcondition, is switched to red light (red illumination), and othermeasurement conditions appropriate for X mark measurement (secondconditions) are similarly set (step S123), and position measurement ofthe X mark Mx2 of the second sample shot SA2 is performed (step S124).

Similarly for the third and fourth sample shots SA3 and SA4, for examplethe wavelength band of the illumination light, as one alignmentmeasurement condition, is switched to broad-band white light (broad-bandillumination), and other parameters are similarly set to measurementconditions appropriate for Y mark measurement (first conditions) (stepsS131 and S141), and position measurements of the Y marks My3 and My4 forthe third and fourth sample shots SA3 and SA4 are performed (step S132and S142). Next, for example the wavelength band of the illuminationlight, as one alignment measurement condition, is switched to red light(red illumination), and other parameters are similarly set tomeasurement conditions appropriate for X mark measurement (secondconditions) (steps S133 and S143), and position measurements of the Xmarks Mx3 and Mx4 for the third and fourth sample shots SA3 and SA4 areperformed (step S134 and S144).

By repeating the above processing, and measuring in order each of themarks Mx1, My1, Mx2, My2, Mx3, My3, Mx4, My4 for the sample shots SA1 toSA4 set on the wafer W, alignment mark position measurements arecompleted. The measured coordinate values are supplied to thecomputation unit 304 via the alignment data storage portion 303 of themain control system 300. The computation unit 304 uses, for example, theleast-squares method to determine parameters satisfying the prescribedEGA calculation formulae, set in advance, from the design coordinatevalues of the marks and the measured coordinate values. Then, thecomputation unit 304 applies the parameters thus determined and thedesign array coordinate values for the shot areas ESi to the EGAcalculation formulae, to determine the calculated array coordinatevalues for each shot area ESi.

Thereafter, exposure processing is performed based on the arraycoordinate values thus obtained. When performing array processing, thebaseline value, which is the difference between the calculation centerof the alignment sensor 200 and the reference point in the exposurefield of the projection optical system PL, has been determined inadvance. The system controller 307 performs positioning in order of eachof the shot areas ESi based on calculated coordinate values obtained byperforming correction of the baseline value for the array coordinatescalculated by the computation unit 304, and performs exposure using thepattern image of the reticle R.

Thus by means of this processing example, measurement conditions areswitched for each layer measured (or in other words, for each X mark andY mark; or in still other words, for measurements in the X-axisdirection and in the Y-axis direction), so that measurements can beperformed under the optimum conditions for each measurement object mark.Hence images of each mark are captured appropriately, and the markpositions are measured appropriately, so that positions can be measuredprecisely, and high-precision alignment can be performed.

Second Processing Example

As the second processing example of the exposure apparatus 100,processing is performed to detect the positions of each of the shotareas on the wafer W by the EGA method, similarly to the above-describedfirst processing example; a method is described of continuouslydetecting the positions of alignment marks for each shot area, either bylayer or by mark type (for alignment marks for the X-axis direction andfor the Y-axis direction). The wafer W being processed, the array ofshot areas, the selected sample shots, and the marks for positiondetect, are all the same as in the above-described first processingexample.

FIG. 8 is a flowchart showing the flow of processing in the markposition measurement method of the second processing example. First, thesystem controller 307 of the main control system 300 decides onalignment measurement conditions (first conditions) to be used by thealignment sensor 200 and main control system 300 to enable positionmeasurement of the Y-axis direction alignment marks (Y marks) My1 to My4for four sample shot areas SA1 to SA4 under the most desirablemeasurement conditions, and sets these conditions (step S211).

Alignment measurement conditions for selection (switching) and settingmay include, for example, the amount of light emitted by the lightsource 241 for illumination light and by the light source 255 for indexplate illumination light. Further conditions may be the contractionstates of the illumination field diaphragm 244, illumination aperturediaphragm 246, imaging aperture diaphragm 249 (or the imaging aperturediaphragm comprising a ring-shaped blocking portion, described above),and index illumination field diaphragm 257. By controlling thesecomponents, the illumination conditions (normal illumination/modifiedillumination), dark-field/bright-field detection method, the numericalaperture N.A. and σ of the optical system, the illumination lightquantity, and other settings can be controlled. Furthermore, bycontrolling the filter used in the wavelength selection mechanism 243,the wavelength of illumination light (measurement light) can beselected. And, as other alignment measurement conditions, theillumination aperture diaphragm can be modified from an illuminationaperture diaphragm 246 having a normal circular transmission portion toan illumination aperture diaphragm 263 having a ring-shaped transmissionportion 263 a such as that shown in FIG. 3A, and, by positioning a phasedifference plate 264 at a position in proximity to the imaging aperturediaphragm 249 beyond the imaging aperture diaphragm 249, control can beexecuted so that the alignment sensor 200 can be made to function as aphase difference microscope type sensor.

Signal processing conditions are also included as alignment measurementconditions, among which are selection of the waveform analysis (waveformprocessing) algorithm used by the FIA computation unit 301 of the maincontrol system 300, the EGA calculation model used by the computationunit 304, and other signal processing algorithms, and selection of thevarious parameters used by each of the selected signal processingalgorithms.

In this processing example, one alignment measurement condition (anexample of one first condition) is, for example, optimization of thewavelength of illumination light in the alignment sensor 200. Asdescribed above, the Y marks My1 to My4 formed on the wafer W forprocessing are marks formed on the uppermost layer of the pattern layerswhich are layered on the wafer W, and there is no particular need tolimit the wavelength of the observation light (illumination light) usedto observe the marks, so that broad-band white light may be used forobservations. Hence the system controller 307 makes settings (executescontrol) of the wavelength selection mechanism 243 such that a beam withwavelengths at 530 to 800 nm (white light) is transmitted within thewavelength selection mechanism 243 of the alignment sensor 200.

When measurement conditions have been set, position measurements of theY marks My1 to My4 of the first through fourth sample shots SA1 to SA4are performed continuously in order (Y-axis direction positionmeasurements) (steps S212-S215).

First, the system controller 307 of the main control system 300 movesthe wafer stage 109 via the wafer stage controller 308 based on the shotmap stored in the shot map data portion 306, and positions the Y markmy1 for position measurement in the Y-axis direction, provided for thesample shot SA1, within the measurement field of the alignment sensor200. When the Y mark My1 is positioned within the measurement field, themain control system 300 performs image capture of the Y mark My1 underthe optimum measurement conditions, while controlling the measurementconditions of the alignment sensor 200, and performs positionmeasurement thereof (step S212).

That is, illumination light emitted from the light source 241, which haspassed through the wavelength selection mechanism 243 and illuminationfield diaphragm 244, irradiates the area for detection comprising the Ymark My1. Light reflected from the area for detection then passesthrough the imaging aperture diaphragm 249 and index plate 252 andsimilar, is received by the image capture device 254, and by means ofphotoelectric conversion, the image capture signal is generated. Theimage capture signal for the Y mark My1 thus obtained is transferredfrom the alignment sensor 200 to the main control system 300, and isstored in the waveform data storage device 302 of the main controlsystem 300.

The image capture signal stored in the waveform data storage device 302is read by the FIA computation unit 301, and signal processing isperformed according to the signal processing conditions set in stepS211, that is, using the preset processing algorithms and parameters. Asa result, the Y mark My1 is extracted from the image capture signal, andthe position of the mark is detected. The position information(coordinate value) of the detected Y mark My1 is stored in the alignmentdata storage portion 303. By this means, position measurement processingfor the Y mark My1 of the first sample shot SA1 is completed.

When position measurement of the Y mark My1 for the first sample shotSA1 is completed, next position processing for the Y mark My2 of thesecond sample shot SA2 is performed (step S213). The system controller307 of the main control system 300 moves the wafer stage 109 via thewafer stage controller 308 based on the shot map stored in the shot mapdata portion 306, based on the coordinate of the Y mark My1 for thefirst sample shot SA1 which is the current measurement object, therelative design value of the coordinate of the Y mark My2 for the secondsample shot SA2 which is the next measurement object, and positioninformation for the Y mark My1 of the first sample shot SA1 which hasbeen measured, so that the Y mark My2 of the second sample shot SA2 ispositioned within the measurement field of the alignment sensor 200.

Then, when the Y mark My2 is positioned within the measurement field,processing similar to the above-described measurement processing for theY mark My1 of the first sample shot SA1 is performed, while the maincontrol system 300 controls the measurement conditions of the alignmentsensor 200, to perform image capture and position measurement of the Ymark My2 under the optimum measurement conditions. At this time, theimmediately preceding measurement object mark is a Y mark for use inalignment in the same Y-axis direction as the mark which is the currentmeasurement object; hence the same measurement conditions can be appliedto perform measurement. That is, measurement of the Y mark My2 can beperformed immediately following the Y mark My1, without modifying themeasurement conditions.

Similarly, when position measurement of the Y mark My2 for the secondsample shot SA2 is completed, the system controller 307 of the maincontrol system 300 positions the Y mark My3 for the third sample shotSA3 within the measurement field of the alignment sensor 200, based onthe shot map stored in the shot map data portion 306, and performsposition measurement of the Y mark My3 for the third sample shot SA3(step S214). Furthermore, when position measurement of the Y mark My3for the third sample shot SA3 is completed, the Y mark My4 for thefourth sample shot SA4 is positioned within the measurement field of thealignment sensor 200, and position measurement of the Y mark My4 for thefourth sample shot SA4 is performed (step S215).

When position measurements of each of the Y marks My1 to My4 for thefirst through fourth sample shots SA1 to SA4 are completed, nextposition measurements of each of the X marks Mx1 to Mx4 for the firstthrough fourth sample shots SA1 through SA4 are performed. To this end,the system controller 307 of the main control system 300 decides andsets the optimum alignment measurement conditions (second conditions)such that position measurements of the X marks Mx1 to Mx4 can beperformed under the optimum measurement conditions (step S221).

In this processing example, similarly to the position measurements forthe Y marks My1 to My4, the wavelength of the illumination light in thealignment sensor 200 is optimized as a measurement condition (an exampleof a second condition). The X marks Mx1 to Mx4 formed on the wafer W forprocessing are marks formed in the layer one below the uppermost layerof the pattern layers which are layered on the wafer W, as describedabove, and so in order to appropriately observe these marks, it ispreferable that observation light (illumination light) be used which hashigh transmissivity which respect to the material of the uppermostlayer. Here, such observation light is assumed to be for examplered-colored light. In this case, the system controller 307 makessettings (executes control) in the wavelength selection mechanism 243such that a filter which transmits a beam of wavelength 710 to 800 nm(red light) is selected in the wavelength selection mechanism 243 of thealignment sensor 200.

When the measurement conditions have been set, position measurements ofthe X marks Mx1 to Mx4 for the first through fourth sample shots SA1 toSA4 (X-axis direction position measurements) are performed continuouslyin order (steps S222 to S225).

Similarly to measurement of the Y mark My1, the system controller 307 ofthe main control system 300 moves the wafer stage 109 via the waferstage controller 308 based on the shot map stored in the shot map dataportion 306, and positions the X mark Mx1 for position measurement inthe X-axis direction, provided for the sample shot SA1, within themeasurement field of the alignment sensor 200. The main control system300 then captures an image and performs measurement of the X mark Mx1under the optimum measurement conditions, while controlling themeasurement conditions of the alignment sensor 200 (step S222).

That is, red illumination light emitted from the light source 241 andpassed through a red filter of the wavelength selection mechanism 243irradiates an area for detection comprising the Y mark My1. Lightreflected from the area for detection is then received by the imagecapture device 254 via the imaging aperture diaphragm 249, index plate252 and similar, and through photoelectric conversion an image capturesignal is generated. The image capture signal for the X mark Mx1 thusobtained is transferred from the alignment sensor 200 to the maincontrol system 300, and is stored in the waveform data storage device302 of the main control system 300.

The image capture signal stored in the waveform data storage device 302is read by the FIA computation unit 301, and signal processing isperformed according to the signal processing conditions set in stepS221, that is, according to the preset processing algorithms andparameters. As a result, the X mark Mx1 is extracted from the imagecapture signal, and the mark position is detected. Position informationfor the detected X mark Mx1 (a coordinate value) is stored in thealignment data storage portion 303. By this means, position measurementprocessing of the X mark Mx1 for the first sample shot SA1 is completed.

When position measurement of the X mark Mx1 for the first sample shotSA1 is completed, next position measurement for the X mark Mx2 for thesecond sample shot SA2 is performed (step S223). The system controller307 of the main control system 300 moves the wafer stage 109 via thewafer stage controller 308 so that the X mark Mx2 of the second sampleshot SA2 is positioned within the measurement field of the alignmentsensor 200, based on the shot map stored in the shot map data portion306, and based on the coordinate of the X mark Mz1 for the first sampleshot SA1 which is the current measurement object, the design relativevalue of the coordinate of the X mark Mx2 for the second sample shot SA2which is the next measurement object, and position information for the Xmark Mx1 for the first sample shot SA1 which has just been measured.

When the X mark Mx2 has been positioned within the measurement field,the main control system 300 performs processing similar to themeasurement processing described above for the X mark Mx1 for the firstsample shot SA1, while controlling the measurement conditions of thealignment sensor 200, and by this means performs image capture andposition measurement of the X mark Mx2 under optimum measurementconditions. At this time, the immediately preceding measurement objectmark is an X mark, used for alignment in the same X-axis direction as isthe mark which is next to be measured, and so the same measurementconditions can be applied to perform measurement. That is, immediatelyfollowing the X mark Mx1, measurement of the X mark Mx2 can beperformed, without modifying the measurement conditions.

Similarly, when position measurement of the X mark Mx2 for the secondsample shot SA2 is completed, the system controller 307 of the maincontrol system 300 positions the X mark Mx3 for the third sample shotSA3 within the measurement field of the alignment sensor 200 based onthe shot map stored in the shot map data portion 306, and performsposition measurement of the X mark Mx3 for the third sample shot SA3(step S224). When position measurement of the X mark Mx3 for the thirdsample shot SA3 is completed, the X mark Mx4 for the fourth sample shotSA4 is positioned within the measurement field of the alignment sensor200, and position measurement is performed for the X mark Mx4 for thefourth sample shot SA4 (step S225).

By means of the above processing, position measurements of the marks My1to My4 and Mx1 to Mx4 for the sample shots SA1 to SA4, provided on thewafer W, are completed. The measured coordinate values are supplied tothe computation unit 304 via the alignment data storage portion 303 ofthe main control system 300. The computation unit 304 uses for examplethe least-squares method to determine parameters satisfying prescribedEGA formulae, set in advance, from the design coordinate values of themarks and the measured coordinate values. The computation unit 304 thenapplies the parameters thus determined and the design array coordinatevalues for each of the shot areas ESi to the EGA formulae, anddetermines the calculated array coordinate values for each shot areaESi.

Then, exposure processing is performed based on the array coordinatevalues thus determined. When performing exposure processing, thebaseline values, which are the intervals between the calculation centerof the alignment sensor 200 and reference points within the exposurefields of the projection optical system PL, are determined in advance.The system controller 307 then performs baseline value correction of thearray coordinates computed by the computation portion 304, and based onthe calculated coordinate values obtained, positions each of the shotareas ESi in order, and performs exposure to transfer pattern images ofthe reticle R onto each shot area. When exposure of all shot areas onone wafer W is completed, the wafer W is removed, and the next waferfrom the same lot is subjected to similar processing.

In this processing example also, similarly to the first processingexample, measurement conditions are switched for each layer (in otherwords, for X marks and for Y marks; in still other words, for X-axisdirection measurements and for Y-axis direction measurements), so thatmeasurements of each measurement object mark can be performed under theoptimum conditions. Hence image capture is performed appropriately foreach mark, and the position is measured appropriately, so that positionscan be measured with high precision, and highly precise alignment can beperformed. Furthermore, by means of this processing example, oncemeasurement conditions for Y-axis direction marks (in the uppermostlayer), or measurement conditions for X-axis direction marks (in thelower one below the uppermost layer), are set, the Y-mark measurementsor X-mark measurements are performed continuously for all measurementshots (sample shots). Hence there is no need to modify the measurementconditions for measurement of each mark as in the first processingexample (measurement conditions need be modified only once), and markscan be measured in order efficiently. That is, by using this processingto perform mark measurements, drops in throughput due to optimization ofmeasurement conditions can be prevented.

Third Processing Example

As a third processing example for the exposure apparatus 100,measurement processing of the baseline value is described. The finalposition information used in controlling the position of the wafer stage109 in order to perform exposure of each of the shot areas on the waferW comprises values obtained by correcting position information for eachof the shot areas computed using EGA based on the position measurementresults of the alignment sensor 200 using baseline values, which aredifferences between reference positions within measurement fields of thealignment sensor 200 and reference positions within the projectionfields of the projection optical system. In the above-described firstprocessing example and second processing example, as a mark measurementmethod of this invention, different measurement conditions for eachlayer (in the X-axis direction and in the Y-axis direction) were usedfor mark detection and for position measurement; but as the baselinevalue used for the position information detected in this way, it ispreferable that baseline values measured under the same measurementconditions as the alignment measurement conditions used by the alignmentsensor be used. That is, when measurements are performed under differentmeasurement conditions in the X-axis direction and in the Y-axisdirection in the alignment sensor 200, as described above, it isappropriate that the baseline values applied to these measurements alsobe detected separately under the same conditions as the measurementconditions when performing position measurements (for each layer, orseparately for the X-axis direction and for the Y-axis direction). Inthis processing example, processing to determine these baseline valuesis described, referring to FIG. 9.

FIG. 9 is a flowchart showing the flow of processing for baselinemeasurement, as the third processing example. In the baselinemeasurement processing described by the flowchart of FIG. 9, first thebaseline value in the Y-axis direction is computed (steps S311 to S313).To this end, the system controller 307 of the main control system 300detects alignment measurement conditions (control conditions)appropriate for measurement of the positions of Y marks Myi in each ofthe shot areas of the wafer, and sets the measurement conditions tothese same conditions (step S311). Here, similarly to the first andsecond processing examples, conditions are decided such that broad-bandwhite light is used as the illumination light of the alignment sensor200, and in actuality the illumination wavelength of the alignmentsensor 200 is switched.

Then, measurement of the baseline in the Y-axis direction (BCHK:baseline check) is performed (step S312). That is, first the systemcontroller 307 of the main control system 300 moves the wafer stage 109,and positions a wafer fiducial mark WFM on the reference plate 110provided on the wafer stage 109 within the field of the reticlealignment system 106, and measures the Y-axis direction positioninformation. Next, the system controller 307 of the main control system300 moves the wafer stage 109, and positions the wafer fiducial mark WFMof the reference plate 110 provided on the wafer stage 109 within themeasurement field of the alignment sensor 200. Then, while controllingthe measurement conditions of the alignment sensor 200, the main controlsystem 300 measures the position in the Y-axis direction of the waferfiducial mark WFM. The wafer fiducial mark WFM used here may be a markcommon to the X and Y axes (mark for two-dimensional measurement), ormay be a mark for use only in Y-axis direction measurement (mark forone-dimensional measurement).

Then, in the system controller 307 of the main control system 300, theY-direction distance between the optical axis of the alignment sensor200 and the optical axis AX of the projection optical system PL isdetected from this measured position information, and the result is usedas the Y-direction baseline value (BCHK value) (step S313).

When computation of the baseline value in the Y-axis direction iscompleted, computation of the baseline value in the X-axis direction isperformed (steps S321 to S323). The system controller 307 of the maincontrol system 300 detects alignment measurement conditions (controlconditions) to appropriately perform position measurement of the X marksMxi for each shot area of the wafer, and sets the same measurementconditions as these (step S321). Here, similarly to the first and secondprocessing examples, conditions are set such that red light is used asthe illumination light of the alignment sensor 200.

Then, measurement of the baseline in the X-axis direction (BCHK:baseline check) is performed (step S322). That is, first the systemcontroller 307 of the main control system 300 moves the wafer stage 109to position the wafer fiducial mark WFM of the reference plate 110provided on the wafer stage 109 within the field of the reticlealignment system 106, and measures the position information in theX-axis direction. Next, the system controller 307 of the main controlsystem 300 moves the wafer stage 109 to position the wafer fiducial markWFM of the reference plate 110 provided on the wafer stage 109 in themeasurement field of the alignment sensor 200. The main control system300 then measures the position in the X-axis direction of the waferfiducial mark WFM, while controlling the measurement conditions of thealignment sensor 200. The wafer fiducial mark WFM used here may be amark common to both the X and Y axes (mark for two-dimensionalmeasurement), or may be a mark for use only in X-axis directionmeasurement (mark for one-dimensional measurement).

Then, in the system controller 307 of the main control system 300, theposition information thus measured is used to detect the distance in theX direction between the optical axis of the alignment sensor 200 and theoptical axis AX of the projection optical system PL, and this is takento be the X-direction baseline value (BCHK value) (step S323).

Each of the baseline values in the X-axis direction and Y-axis directionmeasured in this way may be used to convert position information foreach direction measured using the alignment sensor 200 into positioninformation for a coordinate system with reference to the optical axisAX of the projection optical system PL when, for example, positionmeasurements are performed under different measurement conditions forthe X-axis direction and for the Y-axis direction, as in theabove-described first and second processing examples.

In this way, baseline values are measured separately under conditionsaccording to the measurement conditions for each of the X-axis directionand the Y-axis direction, and are held separately; by this means,appropriate conversion (correction) of position information values canbe performed for mark position information results in the direction foreach axis, so that so-called baseline errors can be suppressed. Hencehigh-precision alignment can be performed.

Fourth Processing Example

Similarly to the above-described first and second processing example, inthis case the measurement conditions are switched during a series ofalignment processing; but when the details of the measurement conditionswitching entail switching of filters in the wavelength selectionmechanism 243, for example, or optical or mechanical movement such asmovement of the phase difference plate 264, there is the possibilitythat such switching may be accompanied by errors in baseline values orsimilar. In order to cope with such situations, each time measurementconditions are switched, it is sufficient to execute baselinemeasurements even when processing wafers in the same lot. The fourthmeasurement example indicates processing to detect the positions of shotareas on the wafer W using the EGA method, while appropriatelyperforming baseline measurements.

FIG. 10 is a flowchart showing the flow of processing in the markposition measurement method presented as the fourth processing example.This processing is essentially the same as the processing examplepresented as the above-described second processing example (FIG. 8). Adifference between the processing in the fourth processing example andthe second processing example is the fact that, when the alignmentmeasurement conditions are modified, immediately thereafter the baselinevalue to be used is re-measured. Specifically, a step of re-measuringthe baseline value in the Y-axis direction (step S412), and a step ofre-measuring the baseline value in the X-axis direction (step S422), areadded. In step S412, the baseline value is measured under the alignmentconditions set in step S411 (first conditions); in step S422, thebaseline value is measured under the alignment conditions set in stepS421 (second conditions). The baseline value measurement method is thatalready described referring to FIG. 9; the other steps are as alreadydescribed referring to FIG. 8, and so a description is here omitted.

By thus performing baseline measurements each time there is modificationof the measurement conditions of the alignment sensor 200, even whenslight fluctuations in the baseline or similar occur due to switching ofmeasurement conditions, such fluctuations can immediately beaccommodated, and as a result mark positions can be measured with highprecision, and precise alignment can be performed.

These embodiments are described so as to facilitate understanding of theinvention, and the invention is in no way limited to these embodiments.Each of the elements disclosed in the embodiments comprises all thedesign modifications and equivalent elements belonging to the technicalscope of the invention, and various arbitrary appropriate modificationsare possible.

For example, the configuration of the exposure apparatus 100, theconfiguration of the alignment sensor 200, and the configuration of themain control system 300, are not limited to the configurations shown inFIG. 1, FIG. 2, and FIG. 4 respectively.

In these embodiments, an off-axis type FIA system (imaging alignmentsensor) was used as the alignment sensor 200 in descriptions; but othermark detection systems may be used . . . . That is, TTR(Through-The-Reticle) type devices, TTL (Through-The-Lens) type devices,or off-axis type devices may be used, and moreover in addition toimaging methods (image processing methods) adopting FIA or similar asthe detection method, for example methods employing diffracted light orscattered light for detection may be used. For example, an alignmentsystem may be employed in which an alignment mark on the wafer may beirradiated substantially perpendicularly with a coherent beam, anddiffracted light of the same orders (±1st, ±2nd, . . . , ±nth orderdiffracted light) from the mark may be caused to interfere to performdetection. In this case, diffracted light is detected independently bythe diffraction order, and the detection results for at least onediffraction order may be used; or, a plurality of coherent beams withdifferent wavelengths may be used to irradiate the alignment mark, anddiffracted light of each order may be caused to interfere for eachwavelength to perform detection.

Furthermore, the exposure apparatus is not limited to the step-and-scantype exposure apparatus of the above embodiments; the invention can beapplied entirely similarly to various other types of exposure apparatus,such as step-and-repeat type and proximity type exposure apparatuses(X-ray exposure apparatuses and similar). Furthermore, the illuminationlight (or energy beam) used for exposure in the exposure apparatus isnot limited to ultraviolet beams, but may be X rays (including EUVlight), as well as electron beams, ion beams, and other charged particlebeams or similar. Furthermore, the exposure apparatus may be used in themanufacture of DNA chips, masks, reticles, and similar.

This application relates to and claims priority from Japanese PatentApplication No. 2004-128536, filed on Apr. 23, 2004, the entiredisclosure of which is incorporated herein by reference.

The invention claimed is:
 1. A measurement method, of using ameasurement system to measure a plurality of X marks and a plurality ofY marks as measurement objects formed on a prescribed substrate,comprising: a first process of setting a measurement condition for themeasurement system to a first condition when measuring, with themeasurement system, all of the X marks among the marks which are themeasurement objects on the prescribed substrate without measuring the Ymarks under the first condition, the X marks including all marks formeasuring positions in a first direction in a two-dimensional place onthe substrate, the Y marks including all marks for measuring positionsin a second direction orthogonal to the first direction in thetwo-dimensional plane on the substrate; a second process, aftermeasuring all of the X marks on the prescribed substrate under the firstcondition, of switching the measurement condition from the firstcondition and setting a second condition; and a third process ofmeasuring, with the measurement system, all of the Y marks withoutmeasuring the X marks, under the second condition.
 2. The measurementmethod according to claim 1, wherein the X marks are marks formed on afirst layer disposed on the substrate, and the Y marks are marks formedon a second layer disposed on the substrate and different from the firstlayer.
 3. An exposure method, of transferring a pattern formed on a maskto a substrate, comprising: a process of using the measurement methodaccording to claim 1, to measure the positions of marks formed on themask or on the substrate, and of positioning the mask or the substratebased on the measurement result.
 4. A measurement apparatus thatmeasures measurement objects on a body by means of the measurementmethod according to claim
 1. 5. The measurement method according toclaim 1, wherein: each of the X marks has line patterns that extend in aY direction; each of the Y marks has line patterns that extend in an Xdirection, the X direction being orthogonal to the Y direction.
 6. Ameasurement method, of using a measurement system comprising anillumination optical system which illuminates a plurality of X marks anda plurality of Y marks, which are measurement objects formed on aprescribed substrate, with an illumination beam, and a light-receivingoptical system which receives the beam from the marks, wherein themeasurement system comprises, as a measurement condition which can bemodified when measuring the marks, a light quantity of the illuminationbeam, NA or σ of the illumination optical system, an insertion orretraction of a phase-imparting member which imparts a prescribed phasedifference to a diffraction beam of prescribed order arising from themarks, into or out of the optical path of the light-receiving opticalsystem, and a signal processing condition when processing aphotoelectric conversion signal obtained upon receiving the beam arisingfrom the marks, the method comprising: when measuring the X marks on theprescribed substrate with the measurement system without measuring the Ymarks, setting the measurement condition of the measurement system to afirst condition, the X marks including all marks for measuring positionsin a first direction in a two-dimensional plane on the substrate; andwhen measuring the Y marks on the prescribed substrate with themeasurement system without measuring the X marks, setting themeasurement condition of the measurement system to a second conditiondifferent from the first condition, the Y marks including all marks formeasuring positions in a second direction orthogonal to the firstdirection in the two-dimensional plane on the substrate.
 7. A method formeasuring a plurality of X marks and a plurality of Y marks formed on asubstrate by using a measurement system, the method comprising: settinga measurement condition for the measurement system to a first condition;measuring, with the measurement system, positions of all of the X marksunder the first condition without measuring the Y marks, the X marks formeasuring positions on the substrate in a first direction in atwo-dimensional plane, the Y marks for measuring positions on thesubstrate in a second direction orthogonal to the first direction in thetwo-dimensional plane; switching the measurement condition from thefirst condition to a second condition after the measurement of all ofthe X marks; and measuring, with the measurement system, positions ofall of the Y marks under the second direction without measuring the Xmarks.
 8. An exposure method for transferring a pattern formed on a maskto a substrate, comprising: measuring positions of marks formed on themask or the substrate by using the method according to claim 7; andpositioning the mask or the substrate based on a result of themeasurement.
 9. A measurement apparatus that measures a measurementobject on a body by using the method according to claim
 7. 10. Ameasurement method comprising: measuring a plurality of X marks on asubstrate with a measurement system under a first condition withoutmeasuring the Y marks, the X marks each having line patterns that extendin a Y direction, the Y marks having line patterns that extend in an Xdirection, the X direction being orthogonal to the Y direction; aftermeasuring X marks on the substrate under the first condition, switchingthe measurement condition from the first condition to a secondcondition, the second condition being different from the firstcondition; and measuring the Y marks on the substrate with themeasurement system under the second condition without measuring the Xmarks.
 11. An exposure method comprising: measuring positions of marksformed on a mask or a substrate by using the measurement methodaccording to claim 10; positioning the mask or the substrate based onthe measurement result; and transferring a pattern formed on the maskonto the substrate.
 12. A measurement method, of using a measurementsystem to measure a plurality of X marks and a plurality of Y marks asmeasurement objects formed on a prescribed substrate, comprising: afirst process of setting a measurement condition for the measurementsystem to a first condition when measuring, with the measurement system,all of the Y marks among the marks which are the measurement objects onthe prescribed substrate without measuring the X marks under the firstcondition, the X marks including all marks for measuring positions in afirst direction in a two-dimensional plane on the substrate, the Y marksincluding all marks for measuring positions in a second directionorthogonal to the first direction in the two-dimensional plane on thesubstrate; a second process, after measuring all of the Y marks on theprescribed substrate under the first condition, of switching themeasurement condition from the first condition and setting a secondcondition; and a third process of measuring, with the measurementsystem, all of the X marks without measuring the Y marks, under thesecond condition.
 13. The measurement method according to claim 12,wherein the X marks are marks formed on a first layer disposed on thesubstrate, and the Y marks are marks formed on a second layer disposedon the substrate and different from the first layer.
 14. An exposuremethod, of transferring a pattern formed on a mask to a substrate,comprising: a process of using the measurement method according to claim12, to measure the positions of marks formed on the mask or on thesubstrate, and of positioning the mask or the substrate based on themeasurement result.
 15. A measurement apparatus that measuresmeasurement objects on a body by means of the measurement methodaccording to claim
 12. 16. The measurement method according to claim 12,wherein: each of the X marks has line patterns that extend in a Ydirection; each of the Y marks has line patterns that extend in an Xdirection, the X direction being orthogonal to the Y direction.
 17. Amethod for measuring a plurality of X marks and a plurality of Y marksformed on a substrate by using a measurement system, the methodcomprising: setting a measurement condition for the measurement systemto a first condition; measuring, with the measurement system, positionsof all of the Y marks under the first condition without measuring the Xmarks, the X marks for measuring positions on the substrate in a firstdirection in a two-dimensional plane, the Y marks for measuringpositions on the substrate in a second direction orthogonal to the firstdirection in the two-dimensional plane; switching the measurementcondition from the first condition to a second condition after themeasurement of all of the Y marks; and measuring, with the measurementsystem, positions of all of the X marks under the second conditionwithout measuring the Y marks.
 18. An exposure method for transferring apattern formed on a mask to a substrate, comprising: measuring positionsof marks formed on the mask or the substrate by using the methodaccording to claim 17; and positioning the mask or the substrate basedon a result of the measurement.
 19. A measurement apparatus thatmeasures a measurement object on a body by using the method according toclaim
 17. 20. A measurement method comprising: measuring Y marks on asubstrate with a measurement system under a first condition withoutmeasuring X marks on the substrate, the X marks each having linepatterns that extend in a Y direction, the Y marks each having linepatterns that extend in an X direction, the X direction being orthogonalto the Y direction; after measuring the Y marks on the substrate underthe first condition, switching the measurement condition from the firstcondition to a second condition, the second condition being differentfrom the first condition; and measuring the X marks on the substratewith the measurement system under the second condition without measuringthe Y marks.
 21. An exposure method comprising: measuring positions ofmarks formed on a mask or a substrate by using the measurement methodaccording to claim 20; positioning the mask or the substrate based onthe measurement result; and transferring a pattern formed on the maskonto the substrate.